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Are there more people alive today than have ever lived?
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​ Are there more people alive today than have ever lived?​
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Since humans haven't been keeping meticulous population records for the vast majority of our time on Earth, we need to estimate our numbers using three key assumptions: the length of time humans have been around, the population sizes at different points in history, and the birth rates (number of births per 1,000 population) during those periods.
If we're defining human as Homo sapiens, then the latest evidence suggests we popped up around 190,000 B.C.E. To keep things simple, we'll say there were two humans at the start – a metaphorical Adam and Eve.
According to the United Nations and other sources, humans had a population of around 5 million by 8,000 B.C.E. For the next 8,000 years, it's estimated that humans had a sluggish 0.05% annual growth rate. This assumption is based on the difficulties of surviving in a time without modern medicine and robust food production. The birth rate during this period is estimated to be 80 births per 1,000 population. To put that into perspective, a high birth rate today is around 35-45 per 1,000 population. Most humans around this time had tough (and short) lives, so more children were needed to simply ensure species survival.
As human history progressed, birth rates likely fluctuated as people experienced both bountiful harvests and famines, times of peace and times of war, good health and plagues. But progress in these areas led to a lower birth rate and higher life expectancies, which meant more people of child-bearing ages could produce the next generation. By 1800, the world population passed 1 billion for the first time and has continued to grow to our current 8 billion fellow human beings.
Despite a lack of demographic data for more than 99% of human history, experts are able to take these population estimates and assumptions about birth rates and crunch the numbers to determine how many people have ever lived.
The result? About 117 billion people have ever been born. That means today's living people make up only ~7% of our all-time population.
So while it seems logical that the burst in population in the recent 100 or so years would dwarf the low and slow population growth of most of humanity, the dead have time on their side. That's why it's doubtful the living will ever outnumber the dead.
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​Sources for this week's newsletter​
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📖 Book of the week
​The Demon-Haunted World: Science as a Candle in the Dark by Carl Sagan and Ann Druyan​
Alien abductions, witchcraft, mass hallucinations. All of this is covered (and de-bunked) in this book. But this book is more of a manifesto for scientific thinking. This book was originally published in 1995, but its message still rings true today: Despite living in an information-rich era, there is a rising tide of pseudoscience that is not only leading us astray as a society but also threatening our democratic values. For a preview, check out this excerpt which often makes the rounds on social media because of its uncanny prophesying of the dilemmas we face today.
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​Check out the full list of books I've recommended here.
👀 Catch up on other curious questions
- ​Why do we have emotions?​​
- ​How does carbon dating work?​​
- ​What is vinegar and how does vinegar preserve food?​​
P.S. 🤔 Do you have a question for the newsletter? Click here to submit your question (or reply to this email!)
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